Method and Apparatus for Drilling a Multilateral Well

ABSTRACT

The method and device for forming multilateral wells includes drilling a first lateral well bore and a second lateral well bore; sidetracking on the low side of the first. Subsequently a first production casing string along with the device is run in the well so that the device is positioned adjacent to the first lateral well bore. A second production casing string is run into the well and the device directs the second production casing string into the first lateral well bore.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to a method and apparatus for drilling multilateral wells from a single well bore. Multiple production wells can be established from an initial well head by drilling additional well bores laterally of the main well bore.

Background of the Invention

Current techniques for the formation of multilateral wells require the use of junction boxes which limit the pressure that can be used in fracing operations and are very complex. They are subject to failure and leakage. Failure of the seals is common.

BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

This invention overcomes the deficiencies of the prior art by the use of a solid one-piece multilateral device which is attached to a production casing string. The upper portion of the well is drilled to be able to accommodate two production casing strings. A first lateral wellbore is drilled to a planned total depth. A second internal wellbore is drilled, sidetracking on the low side of the first, to a planned total depth.

Production casing is run into the second wellbore. A multilateral device according to the invention is secured to the production casing and is positioned adjacent to the first well bore. The device includes a RF tag and can be positioned so that the tool face is in the proper orientation with respect to the beginning of the first wellbore.

Once the device is properly positioned, a second production casing string is run into the well. As it reaches the device, the production casing is directed into the first lateral well. The casing is continued to be run in until it reaches the predetermined total depth. Guides are located on the production casing associated with the second well bore to guide the production casing associated with the first well bore.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:

FIG. 1 is a schematic view of the multiple production casings and the multilateral device.

FIG. 2 is a perspective view of an embodiment of the multilateral device.

FIG. 3 is a perspective view of a guide member according to an embodiment of the invention.

FIG. 4 is a schematic view of the main well casing and the lateral production casing strings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A single wellbore is initially drilled and an intermediate casing 41 shown in FIG. 4 is set in the well. The intermediate casing may be for example 13⅜ inch casing. A corresponding hole is drilled below the casing to a suitable depth. The first well bore is drilled with the required directional tools. This wellbore can be a directional and or a horizontal well.

Next a second well bore is drilled sidetracking on the low side of the first wellbore.

A gyro survey is run with both drilling operations. An open hole caliper log along with a GR is also run to ascertain the exact depth where the sidetrack occurred in the second wellbore.

Production casing 11, 12 along with multilateral device 10 and guides 14 is run into the second wellbore as shown in FIG. 1.

A RA tag or equivalent is installed in the device. Prior to the Multilateral Device exiting the intermediate casing, a GR log along with a gyro is used to position the tool on depth and orient the tool face to the same azimuth as the beginning of the “First” wellbore. Numerous length casing pup joints are provided on location for space out purposes. Once the multilateral device is oriented properly and on depth, the casing string is slowly slacked of (i.e., ensuring casing does not turn) and the device positioned as planned. The casing string is set in dual slips on the rig floor to suspend it.

Multilateral device 10 includes a solid intermediate portion 23 and two end collars 22 and 21 as shown in FIG. 2. Collars 22 and 21 are provided with bores 28 and 27 respectively to accommodate production casing 11, 12 as shown in FIG. 1. A side portion of device 10 includes a grooved portion 24, a ramp 25 and a terminal portion 26.

Once production casing 11, 12 is set within the well, production casing string 13 can now be run into the lateral. A false rig floor can be used to ensure that casing running operations stay above the 11, 12 string casing stub. Production casing 13 needs to be passed through bore 33 in guide body 31 of the guide 14 as shown in FIG. 3. Guide 14 may also have rollers 32 to facilitate positioning within the wellbore.

As production casing 13 contacts multilateral device 10, it will engage groove 24 and ride up ramp 25 so as to be laterally deflected into the first previously drilled wellbore.

Once string “13” is in place and set in the dual slips on the floor, cement heads are made up and bottoms up is circulated via both strings. The strings are then cemented in place simultaneously, bringing top of cement into 13⅜″ intermediate string. The BOP's are picked up and dual slips are set in the wellhead to suspend both strings. The BOP's are nippled down and a dual, 41/16″, 10 kpsi (i.e., or as required) tree is installed and tested. The rig is moved off and the well is now prepared for dual completion. 

What is claimed is:
 1. A method of forming multilateral wells comprising: a) drilling a first well bore of sufficient diameter to accommodate two or more production casings, b) drilling a first lateral well bore to a given depth, c) drilling a second well bore sidetracking on the low side of the first lateral well bore, d) providing a multilateral device on a producing casing string and positioning the production casing in the well such that the multilateral device is positioned to guide a second production casing string into the first well bore, and e) running in said second production casing string into the well so that the multilateral device directs the second production casing into the first lateral well.
 2. The method of claim 1 further including the step of cementing in place the two production strings.
 3. The method of claims 1 further including the step of placing an intermediate casing in the first well bore.
 4. A multilateral well tool comprising; a) a solid body having a first end and a second end, b) at least one collar having a first bore adapted to accommodate a first production casing string, c) a groove formed in an exterior surface of the tool for receiving and guiding a second production casing string.
 5. The multilateral well tool as claimed in claim 4 further including a ramp positioned adjacent to the groove for guiding the second production casing string laterally.
 6. The multilateral tool as claimed in claim 4 wherein there are two collars, one located at said first end and one positioned at said second end, each collar having a bore.
 7. The method of claim 1 further including the step of placing a plurality of guides on the first production casing string, the guides having a through bore adapted to receive the second production casing string as it is run into the well.
 8. The method of claim 7 wherein the guides include rollers to facilitate running in and rotational positioning of the first producing casing string. 